


For Want Of A Challenge

by Useless19



Category: Transformers - All Media Types, Transformers: Prime
Genre: Implied/Referenced Prostitution, M/M, Sticky Sexual Interfacing
Language: English
Status: Completed
Published: 2020-04-04
Updated: 2020-04-04
Packaged: 2021-02-28 18:21:24
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,546
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23481628
Author URL: https://archiveofourown.org/users/Useless19/pseuds/Useless19
Summary: Knock Out seduces his way into Megatron's berth as a way to gain a favour or two. It wasn't like their leader had managed to have good sex in the centuries Knock Out had been the medic for Decepticon High Command, so Knock Out should have a clear advantage.No one told him that Megatron used to do thisprofessionally.
Relationships: Knock Out/Megatron (Transformers)
Comments: 25
Kudos: 124





	For Want Of A Challenge

**Author's Note:**

> For anyone waiting on the second chapter of _Reaching For The Stars_ , I'm sorry it's taking so long. Have some completely unrelated MegaKnock smut to make up for the lack of an update.
> 
> I will paddle my way to hell with this pool noodle of a ship.

It had been easy to get here — here being Megatron's berth, where Knock Out was showing off what a good kisser he was. _So_ easy that Knock Out should have done this sooner. It had only taken a few suggestive remarks for Megatron to take the bait and order Knock Out's presence for the evening.

The best way to gain favour was to allow High Command to appreciate your best skills and, while Knock Out's medical and scientific expertise weren't exactly _un_ appreciated, everyone had a special level of appreciation for interfacing skills.

And Knock Out was _good_ at interfacing.

Megatron had muttered something about being rusty as he pulled Knock Out onto the berth, which might not be great for Knock Out's immediate pleasure, but would no doubt make the favour he was about to get even bigger.

Now Knock Out was in Megatron lap, purring promises of how much fun they were going to have.

Megatron bit the seatbelt on Knock Out's neck and tugged lightly. Knock Out revved his engine encouragingly. It wasn't a particularly sensitive spot, but the rough slide of strap was always such a unique sensation and it was interesting that Megatron had thought to try.

Megatron tipped Knock Out over so he was on his back and pulled his thighs apart with heavy, clawed servos.

"How long can you keep your panel shut?" Megatron said, venting hotly over Knock Out's closed array.

"How fast can you get me open, you mean?" Knock Out reengaged the lock on his panels. He certainly didn't mind a bit of foreplay to raise charge for the main event.

"Hmm." Megatron pulled Knock Out closer and grazed his inner thigh with sharp fangs. "Instantly."

Knock Out barely refrained from snorting. Then Megatron licked over his panel and somehow sent a pulse of static electricity through his glossa that popped Knock Out's panel open before he could reroute the energy away from the lock.

"What?" Knock Out gasped as hot glossa assaulted his valve.

"You don't want me to explain," Megatron said. "You want me to spend my time doing something more…" he licked Knock Out's anterior node too teasingly to be anything other than intentional, " _productive_."

"When you put it _that_ way." Knock Out tilted his hips to give Megatron better access. "Yes, please."

"You should show respect more often."

Megatron cupped Knock Out's aft and pressed his mouth against his valve. Slow, firm licks coaxed Knock Out's valve to yield.

Megatron's glossa was surprisingly strong. All too soon he found the trigger spot that was present on every ring of callipers and used it to press Knock Out further open. Most mechs didn't believe the spot even existed. As a medic, Knock Out knew better — and so apparently did Megatron.

Or it was luck. That seemed much more likely.

With the first calliper cycled open, Megatron had much more mesh to lick.

It had been a few months since Knock Out had last been eaten out. Toys just didn't have the same _presence_ as a mech between his legs. He let out an approving moan and fisted his servos to avoid grabbing Megatron's helm and press him deeper.

He had a feeling Megatron wouldn't be a fan of being directed and those were some _sharp_ denta next to his unarmoured mesh.

Megatron shifted his grip back to Knock Out's thighs and spread them as far open as his joints would allow. Thick, heavy claws dug into armoured legs with just enough pressure to heighten arousal with the thrill of danger, but not so much that it would leave nasty scratches.

Knock Out appreciated the courtesy. And he _definitely_ appreciated the licks of a clever glossa; alternating hot swipes over every decimetre of exposed mesh with quick little flicks directly on his anterior node.

Megatron sealed his lips over Knock Out's node and sucked, sending a delightful frisson of pleasure through Knock Out's struts. That was _nice_.

Knock Out let his breakers trip and overloaded with a breathy moan. Fluke had Megatron ebb him perfectly through his overload. Managing to keep that edge of _almost_ too much without ever tipping into oversensitivity.

The evening was still young and — as surprisingly decent as Megatron was at eating valve — Knock Out had to earn that favour somehow. And few mechs considered giving oral the highlight of interface.

Knock Out purred his engine. "Very nice. Now, perhaps we could move on to the main event?"

Megatron pressed his thumbs flat against the rim of Knock Out's valve and spread him open.

"I don't think you can take me yet," Megatron said, then ducked his head back down and _licked_ deep.

His glossa was long and Megatron's faceplates were pressed right up against Knock Out. It was all Knock Out could do to not cry out as Megatron reached nodes previously untouched by glossa. His callipers clenched unsuccessfully on the slippery intrusion.

Despite his previous discharge, Knock Out was approaching another overload with embarrassing speed. His spike extended out of its housing, as an easy way to split the charge and slow things down.

Megatron pulled back sharply — ah, maybe shoving his spike in Megatron's face without warning hadn't been the cleverest thing to do — then, with a huff of amusement, Megatron swallowed Knock Out's entire spike.

For a split-second, Knock Out was concerned about Megatron's viciously sharp denta near less-sensitive but eminently more biteable parts of his anatomy, then Megatron curled his glossa and _sucked_.

Knock Out arched so much his wheels were the only point of contact between his back and the berth. He clamped his brakes and desperately hoped they held as Megatron began to move with perfectly wet suction.

"Oh," Knock Out purred. " _Very_ nice."

He hadn't expected Megatron to be the kind of mech who knew how to deal with a spike.

And he _did_ know. Megatron's glossa drew charge up from base to tip, unerringly following the wiring beneath the plating. All the while keeping everything gloriously wet and warm.

Once, back on Cybertron, Knock Out had seen an experimental light that used a super-conductive liquid to keep a single bolt of electricity arcing back and forth without losing energy. Megatron's mouth felt like that. Charge crackled from Knock Out's spike and wouldn't ground itself anywhere in Megatron's mouth.

Before Knock Out could embarrass himself by overloading down Megatron's intake before he could find the words to warn him, Megatron pulled off and switched back to Knock Out's valve.

His oral lubricant still held some of Knock Out's spike's charge and Knock Out's valve lips nearly went numb from the sudden jolt.

"How?" Knock Out gasped.

Cybertronian mouths were naturally conductive — it was a way of detecting energon quality, if nothing else — any charge should have been grounded already.

Megatron growled something against Knock Out's anterior node.

Answers would have to wait, overload was imminent.

Knock Out manually stopped his spike drawing from his transfluid reserves. He'd have to clean out the piping later, but that was far better than having to clean transfluid off his paint job.

Overload hit a moment later. Electricity burned through Knock Out's wiring and his fuel pump sped up to keep the sensation drawn out for as long as possible.

Again, Megatron kept him just this side of oversensitive. Knock Out shivered as a few late sparks crackled to a stop, then he tensed as Megatron slipped a claw into his valve. Despite the sharpness, Megatron managed to avoid scratching sensitive mesh. Instead, he tested the clench of Knock Out's callipers, finding the manual widening trigger on every last one without apparent difficulty.

" _Now_ you're ready," Megatron said.

He finally let his spike pressurise and ground the impressive length of it against Knock Out's slick valve.

"Wait!" Knock Out said quickly. Things were being far too one-sided. He reached down to wrap a skilful medic's hand around Megatron's spike. "Let me show you how good _my_ mouth is, my liege."

"So far you have failed to impress me," Megatron said, spike still grinding deliciously against Knock Out's anterior node and making his vocaliser reboot.

"Let me do better," Knock Out said. "I want to taste you. Please."

The faux politeness did the trick and Megatron settled himself against the wall, long legs spread, and Knock Out got a good look at what he was working with.

More than proportional, Megatron's spike was a burnished silver and thickly ridged. Purple biolights underlit each ridge, making them appear more prominent, while the tapered tip was angled to catch the deepest nodes in a valve in a way Knock Out had only seen on toys before.

Knock Out wanted that spike in him so much his valve _throbbed_ with it.

But no, first things first. Knock Out had to prove to Megatron that he wasn't all talk and ensure that he had a bit more leeway to go out racing whenever he wanted.

A lick up the shaft, from base to tip, was always a good start. Knock Out wasn't going to be able to take the whole thing down his intake — at least not easily from this angle and certainly not without some good preparation first — but ensuring everything was slick was always a good place to start with a blowjob.

The odd shape of the tip was going to take some getting used to. Well, it had been some time since Knock Out was offered such a challenge in berth. Now was as good a time as any to get back into an adaptive state.

Glossa first, Knock Out slid Megatron's spike into his mouth. Shallowly, to begin with, then twice as deep once he was sure it was wet enough to slide smoothly.

Hot, living metal was uniquely perfect in the mouth.

Megatron laid a heavy servo on Knock Out's helm and pushed him down. His spike nudged the top of Knock Out's intake then Megatron started moving Knock Out on his spike.

Knock Out didn't resist. In a lot of ways this was easier — he didn't have to try to guess a rhythm that Megatron would like — and it meant he could focus on exploring with his digits. Megatron was even decent enough not to ram his spike down Knock Out's intake. A rare quality in warriors Knock Out had fragged previously.

Knock Out eased his claw tips into the thin gaps between platelets on Megatron's spike. The charge was stronger below the surface and Knock Out ramped it up further by encouraging lubricant to drip in.

Megatron let go of Knock Out's helm. "I'm not going to do all the work, Knock Out."

Knock Out debated arguing the point — he was doing plenty of work! — then doubled down on his blowjob instead.

Megatron kept making little grunts of surprise whenever Knock Out tongued the most sensitive spots under the ridges of his spike or switched his rhythm from slow and lots of glossa to fast and lots of oral lubricants or did anything skilful. Did he really have so little faith in Knock Out's interfacing abilities?

Knock Out was going to give him the best overload of his functioning out of spite.

Megatron reached for Knock Out's wheels. Knock Out tensed preemptively — those unfortunate enough to live life without wheels always went right for the wells between the spokes and that was horribly ticklish. A sure-fire way to kill the mood.

But Megatron didn't. He kept to the tyres and pulled the rubber away from the rim and scraped a claw against the hidden metal there.

Knock Out moaned as loud as he could with his mouth full of spike. How did he not know that _that_ was an erogenous zone on his own frame? How the slag did _Megatron_ know it was?

Knock Out pulled off, earning himself a grumble — one mostly for show, if the warm, lazy look in Megatron's optic was any indication.

"Would you like to finish in my mouth or valve?" Knock Out asked, slowly pumping Megatron's spike. "I'd rather not get transfluid on my paint, if you don't mind, my liege."

Megatron gave a hum of contentment and slipped his thumb into Knock Out's mouth.

"I'm curious to see if you can manage to keep this up for an overload," Megatron said.

He laughed when Knock Out glared.

"I assure you, my lord, if I can manage twenty-hour surgeries without losing focus, I can manage to suck spike for less time without a drop in quality."

"Perhaps I should take you up on that offer of a twenty-hour blowjob," Megatron said, cupping Knock Out's helm. "But another time. Come, give me an overload."

He sounded _amused_ at the idea that Knock Out could. Knock Out narrowed his optics and took Megatron back into his mouth.

Knock Out could feel the charge crawling under Megatron's platelets in his mouth. Overload was closer than he was making it out to be. All Knock Out needed to do was figure out what would cause Megatron to have to ground it.

He reached further down with one servo, roughly stroking up the inside of Megatron's armoured thigh. Heavy plating like that needed a good bit of pressure and, thankfully, Knock Out knew some tricks to finding sensitive spots on even warlord-grade armour.

Knock Out pressed the base of his palm against the top Megatron's valve cover and pressed hard. Megatron's spike twitched promisingly.

Knock Out settled into a rhythm of suck, press, lick. Megatron's hips were twitching up minutely.

Very close, but not enough yet.

Knock Out swallowed carefully, then took as much of Megatron's spike into his intake as he could given the angle. He pressed the heel of his servo to the base and rubbed, then revved his engine, focusing on keeping the vibrations high.

Megatron's vocaliser was quiet in overload, but his engine _roared_ hard enough to shake the berth. Hot transfluid flooded Knock Out's glossa with more of a furry tang of zinc than he'd expected — Megatron really was as low-caste as he'd said. Knock Out swallowed, tasting victory, and rubbed Megatron through the rest of his overload.

"Adequate," Megatron said, once he'd finished.

He was venting too hard for there to be much bite to the words. Knock Out stretched and settled into a pose he knew larger bots found irresistible.

"So…" Knock Out traced a claw tip up Megatron's spike. "How long until I can have this inside me?"

Megatron pounced. He threw Knock Out into his back and pressed down, devouring his mouth.

"Refractory is something _other_ mechs have to worry about."

"Well then." Knock Out wrapped his legs around Megatron's waist

Megatron knelt up and cast a lingering look up and down Knock Out's highly polished plating.

"On your front," Megatron ordered. "No, flat." He pressed Knock Out into the berth when he initially went for hands and knees.

"You won't be able to spike me hard from there."

"That's the idea." Megatron lowered himself over Knock Out, hot, slick spike against his aft plating and solid thighs bracketing Knock Out's. "You'll want to keep me out until you're completely ready."

"I can handle your spike," Knock Out snapped, insulted that Megatron thought otherwise.

Megatron lined up the tip of his spike with Knock Out's valve and began to press in.

"Prove it."

 _Primus_ , that was a lot of spike already. Knock Out hurriedly forced his callipers to their maximum capacity and moaned as Megatron slid further in.

It was difficult for any real speed to be built up in this position, so Megatron kept his strokes slow and long, nudging an extra decimetre in every few thrusts. Knock Out took it all and tried not to drool in pleasure.

"Surprising," Megatron noted, still not hilt deep, but getting close now. "I hadn't expected a mech of your size to take me so well."

"I've been DP-ed before," Knock Out said, managing by some miracle to keep his voice steady. Time for some — admittedly true — flattery. "You're only a bit bigger than they were together."

"I've always found multiple berth partners at once a disappointment. They don't have the focus and coordination of a single mech." Megatron pressed in as deep as the position allowed and forced his glossa between Knock Out's tyre and rim.

Knock Out's valve _throbbed_ and he moaned into the sheet metal desperately.

Seriously! How had Knock Out gone this far through life without knowing that there was a spot that would make an automobile overload damn near instantly?

"Frag me," Knock Out managed.

Megatron chuckled and sat back, pulling Knock Out with him by the hips. Now on his hands and knees, with a bit more space for his vents to cycle cool air in, Knock Out mastered himself.

Megatron hilted himself fully — that was a _lot_ of spike — a warning flashed up on Knock Out's HUD, he dismissed it and triggered a rippling pattern of squeezes in his callipers around that wonderfully thick spike. Megatron vented sharply then, after a few teasing, experimental thrusts, started fragging Knock out good and hard.

 _This_ is what Knock Out had expected.

He'd braced himself from the outset that things might just end up with Megatron pounding his poor valve. And it had, but with far more preparation than anyone could have reasonably thought Megatron would have had the patience for, so Knock Out was more than ready for a nice, hard frag.

There wasn't much Knock Out could do from this position. He couldn't reach much of Megatron with his servos, so he was left running through his long inventory of calliper tensing patterns and cataloguing how Megatron reacted to them — first individually, then chaining together longer strings to find the best result.

Megatron gripped Knock Out's tyres and squeezed, claw tips scratching teasingly at the inside rim on each side. He coupled it with slowing his pace drastically, so Knock Out could feel every last ridge of his spike as it rubbed against the edge of his valve.

Knock Out choked and lost his place on his pattern list.

"Don't hold back," Megatron said, mockingly soothing. "Overload."

He used his grip on Knock Out's wheels to pull him back onto his spike with every tortuously slow thrust. It was unbelievably good.

Knock Out was much too close to another overload, however, he could tell from the levels of charge he was reading from Megatron's spike, Megatron was still quite some distance from his next one.

That wouldn't do, but Knock Out couldn't focus on more than his own charge which was threatening to spill over and ground itself on Megatron's spike at any second. He'd have to discharge. But then, he was beautiful in overload, all of his past lovers had said so. So why not use that to help Megatron along?

Knock Out tripped his circuit breakers and overloaded. His optics stopped accepting input and his vocaliser spat a screech of static as emergency subroutines redirected power to deal with the surge.

Megatron continued to drive his spike torturously slowly through Knock Out's rippling callipers. Knock Out caught a cut-off gasp and a murmur of appreciation through ringing audials — Megatron had _liked_ that.

"Not bad," Knock Out said as soon as his vocaliser rebooted.

Megatron growled and pulled out. Knock Out flinched, anticipating a blow, but Megatron only flipped Knock Out over and yanked him back onto his spike. The change in angle pressed the tip perfectly against the deep-set nodes in Knock Out's valve.

"Oh!" Knock Out wrapped his legs around Megatron's waist, thighs clamped tight against solid steel. "There! Right there!"

Megatron ground down shallowly, surprisingly considerate of Knock Out's overstimulated valve.

"I should find something better for your mouth to do than dare to presume to give me orders," Megatron said.

Knock Out's optics started giving feedback again as Megatron slid a clawed thumb into his mouth. That was a predatory gaze being levelled at Knock Out and Megatron's smirk only got sharper when he noticed that Knock Out could see again.

"You're full of surprises, doctor," Megatron said, drawing his thumb in and out of Knock Out's mouth in a crude mimicry of his spike. "I thought you would have given up by now."

Knock Out revved his engine in reply — his glossa was currently occupied — and kicked Megatron's aft with his heel. It made a loud _clang_ , but it wouldn't have hurt Megatron through his armour. Megatron laughed.

"Desperate little thing," he murmured. "I'll give you what you need."

Megatron took his thumb back and braced himself to start building up speed in his thrusts again.

That unfairly perfect spike kept hitting Knock Out in exactly the right place to make his legs squeeze around the solid wall of mech that was currently pounding him into the berth. He wasn't going to overload again until Megatron had — he _wasn't_ — that's what Knock Out had to remember and hold on to.

But just lying back and enjoying the frag was _so_ tempting.

Knock Out arched under Megatron as much as he could with one of Megatron's strong servos gripping his hip and traced his own servo over his headlight, letting them brighten to a soft glow as his digits drifted over the curves of his chassis. Megatron watched with something that Knock Out triumphantly recognised as hunger in his optics.

Megatron's other servo was braced above Knock Out's helm. It was easy for the pointed tips of Knock Out's digits to slip past heavy plating and reach the sensitive circuitry in Megatron's forearm that powered his fusion cannon.

"Careful, Knock Out," Megatron growled. "You wouldn't want something to happen to your paint now, would you."

"Trust me," Knock Out pulled his digits back and licked them to help conductivity, "I'm a professional."

Megatron didn't object further, but he kept a close watch when Knock Out slid his digits back into his arm.

Perhaps not surprisingly, Megatron's cannon and sword arm was one of his better-maintained systems. Knock Out had done plenty of work on it over the centuries and knew where the manual firing and eject switches were. He avoided those, focussing instead on the circuitry that drew power from his other systems to charge up the cannon.

Violet light glowed and reflected off the berth's dull finish, painting Megatron's plating purple, as Knock Out coaxed charge into Megatron's weapon systems. Charge was crackling everywhere. The sheet metal of Megatron's berth hadn't been properly earthed and little arcs of electricity kept zapping Knock Out's plating.

Megatron's cooling fans stuttered. His heavy flight engine thrummed in an attempt to keep up with simultaneous demands for charge from his array and cannon.

"Counterproductive," Megatron grumbled.

"Practised," Knock Out promised. He dug his digits in to restrict the power-flow and pushed up just high enough to lick the Decepticon symbol on Megatron's chest.

The fragging had slowed. Megatron picked up the pace again as his systems compensated for the energy loss, spike properly pressurised once more. And _oh_ , Knock Out wished Cybertronian full-immersive sims were still available. He'd happily upload his datafiles of this encounter and use it for self-service for the next century.

Charge was starting to lick over Megatron's plating again. That should do it.

With a skilful flick, Knock Out sent the built-up charge in Megatron's weapons systems flooding back into the rest of his frame. Knock Out's array _stung_ with the sudden influx of charge from Megatron's spike.

"You —!" Megatron shakily thrust into Knock Out once, twice — and then he was overloading with a roar from both engine and vocaliser.

Knock Out couldn't resist the magnetic pull and crashed over the edge too.

Cooling fans clamoured. Knock Out retracted his claws from Megatron and collapsed in a strutless sprawl. The berth metal was heated from their efforts and Knock Out panted to keep up with his frame's requests to cool down.

Megatron was braced on his forearms above him, panting similarly.

Knock Out shifted and winced as the heavy spike he was still impaled on nudged his sensitive mesh. "Ah, could you —"

"We're not done yet, Knock Out," Megatron said darkly.

There was a _click_ , so quiet Knock Out nearly missed it, then Megatron's spike started _vibrating_.

Knock Out's poor aching callipers decided that it was the best thing to have ever happened and spiralled down tight to feel every last buzz. The deep, long thrusts Megatron started complemented it perfectly.

"M— M—" Knock Out's vocaliser struggled to produce more than a desperate moan.

Overload hit yet again out of nowhere and Knock Out's memory recorder fell offline.

* * *

Knock Out came back online. He was aching and sticky and — was that _transfluid on his plating?!_

Megatron was nowhere in sight, but the sound of a solvent spray was audible through the open door to his washracks.

Knock Out denied his systems requests for more recharge and wobbled to his pedes. His gyros complained and the resulting tilt had him careening into a wall. Knock Out gritted his clutch and stumbled along, using the wall for support, until he reached the washracks' door.

Megatron was scrubbing lubricant off his faceplates under the spray, but amused red optics still glanced over when Knock Out appeared in the doorway.

"Up and about already? I'm rustier than I thought," Megatron said.

"What was that?" Knock Out demanded.

"Interface, doctor. I assume you know what that is."

Knock Out's engine revved in anger before he could help it. "I've never spent that much charge that quickly in all my functioning!" He snapped. "What _was_ that?"

"I take it that you never spent any shanix on a gladiator's time." It wasn't a question. "Ah, you thought our caste beneath your fancy medic notice."

"How would being a gladiator help? That wasn't a fight!"

Megatron stepped out of the spray of solvent and cocked his head in invitation. As furious as Knock Out was, he wasn't about to pass up the chance to clean the transfluid off his plating before it dried on completely — it _stained_ given half a chance.

"My point, Knock Out, is that gladiators brought profit to their masters in more ways than just fighting. The high-caste liked danger when it was leashed for them." Megatron tilted Knock Out's chin up with one long, sharp claw. "And I was Kaon's champion for a thousand years. Undefeated in every arena."

"I've interfaced more times than you have," Knock Out said determinedly.

If nothing else, Knock Out had been out on the town nearly every night before the war back on Cybertron. And it certainly hadn't been _Megatron_ in a serious long-term relationship the entire time they'd been on speaking terms.

"But you didn't have to be _good_ at it," Megatron said. "So the next time you think about trying to best me," the claw under Knock Out's chin curled and pressed harder, just shy of drawing energon, " _reconsider_."

Megatron left Knock Out under the spray and went back into his berthroom to dry off.

Knock Out fumed as he scrubbed his plating. Just because he'd offlined in the middle of things — he'd been taken by surprise, that was all. No one in their right mind would have thought _Megatron_ would be a good frag.

 _Next_ time would be different.

**Author's Note:**

> Want something to do while stuck indoors right now? Try one of my visual novel adaptations of some wonderful Transformers fics at: [transformersvn.tumblr.com](https://transformersvn.tumblr.com)


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